On Nov 26, 2010, at 3:51 AM, Zdenek Dvorak wrote: > Hi, > >> I'm investigating an ICE in loop-iv.c:get_biv_step(). I hope you can shed >> some light on what the correct fix would be. >> >> The ICE happens when processing: >> == >> (insn 111 (set (reg:SI 304) >> (plus (subreg:SI (reg:DI 251) 4) >> (const_int 1)))) >> >> (insn 177 (set (subreg:SI (reg:DI 251)) >> (reg:SI 304))) >> == ... > > loop iv analysis currently does not handle assignments to subregs ... > So, if such a code > gets produced consistently for a large fraction of the loops, it would be > necessary to teach loop-iv to analyze induction variables represented in > subregs. This would mean a more involved rewrite of loop-iv, though,
I see. In that case a simpler way to fix the problem may be to move Tom's extension elimination pass /after/ loop optimizers. Do you (or anyone reading this thread) have suggestions on what would be a good spot in the optimization pipeline for sign- and zero-extension elimination pass? Thanks, -- Maxim Kuvyrkov CodeSourcery +1-650-331-3385 x724
